<s>
The	O
Jenkins	B-Error_Name
hash	I-Error_Name
functions	I-Error_Name
are	O
a	O
collection	O
of	O
(	O
non-cryptographic	O
)	O
hash	B-Error_Name
functions	I-Error_Name
for	O
multi-byte	O
keys	O
designed	O
by	O
Bob	O
Jenkins	O
.	O
</s>
<s>
Jenkins	O
's	O
one_at_a_time	O
hash	B-Error_Name
is	O
adapted	O
here	O
from	O
a	O
WWW	O
page	O
by	O
Bob	O
Jenkins	O
,	O
which	O
is	O
an	O
expanded	O
version	O
of	O
his	O
Dr.	O
Dobb	O
's	O
article	O
.	O
</s>
<s>
Sample	O
hash	B-Error_Name
values	I-Error_Name
for	O
one_at_a_time	O
hash	B-Error_Name
function	I-Error_Name
.	O
</s>
<s>
The	O
avalanche	O
behavior	O
of	O
this	O
hash	B-Error_Name
is	O
shown	O
on	O
the	O
right	O
.	O
</s>
<s>
Each	O
of	O
the	O
24	O
rows	O
corresponds	O
to	O
a	O
single	O
bit	O
in	O
the	O
3-byte	O
input	O
key	O
,	O
and	O
each	O
of	O
the	O
32	O
columns	O
corresponds	O
to	O
a	O
bit	O
in	O
the	O
output	O
hash	B-Error_Name
.	O
</s>
<s>
Colors	O
are	O
chosen	O
by	O
how	O
well	O
the	O
input	O
key	O
bit	O
affects	O
the	O
given	O
output	O
hash	B-Error_Name
bit	O
:	O
a	O
green	O
square	O
indicates	O
good	O
mixing	O
behavior	O
,	O
a	O
yellow	O
square	O
weak	O
mixing	O
behavior	O
,	O
and	O
red	O
would	O
indicate	O
no	O
mixing	O
.	O
</s>
<s>
Only	O
a	O
few	O
bits	O
in	O
the	O
last	O
byte	B-Application
of	O
the	O
input	O
key	O
are	O
weakly	O
mixed	O
to	O
a	O
minority	O
of	O
bits	O
in	O
the	O
output	O
hash	B-Error_Name
.	O
</s>
<s>
Standard	O
implementations	O
of	O
the	O
Perl	B-Language
programming	I-Language
language	I-Language
prior	O
to	O
version	O
5.28	O
included	O
Jenkins	O
's	O
one-at-a-time	O
hash	B-Error_Name
or	O
a	O
hardened	O
variant	O
of	O
it	O
,	O
which	O
was	O
used	O
by	O
default	O
.	O
</s>
<s>
It	O
is	O
the	O
function	O
referred	O
to	O
as	O
"	O
My	O
Hash	B-Error_Name
"	O
in	O
the	O
1997	O
Dr.	O
Dobbs	O
journal	O
article	O
,	O
though	O
it	O
has	O
been	O
obsoleted	O
by	O
subsequent	O
functions	O
that	O
Jenkins	O
has	O
released	O
.	O
</s>
<s>
Applications	O
of	O
this	O
hash	B-Error_Name
function	I-Error_Name
are	O
found	O
in	O
:	O
</s>
<s>
the	O
SPIN	B-Application
model	I-Application
checker	I-Application
,	O
for	O
probabilistic	O
error	O
detection	O
.	O
</s>
<s>
In	O
a	O
paper	O
about	O
this	O
program	O
,	O
researchers	O
Dillinger	O
and	O
Manolios	O
note	O
that	O
lookup2	O
is	O
"	O
a	O
popular	O
choice	O
among	O
implementers	O
of	O
hash	B-Error_Name
tables	O
and	O
Bloom	B-Algorithm
filters	I-Algorithm
"	O
.	O
</s>
<s>
They	O
study	O
lookup2	O
and	O
a	O
simple	O
extension	O
of	O
it	O
that	O
produces	O
96-bit	O
rather	O
than	O
32-bit	O
hash	B-Error_Name
values	I-Error_Name
.	O
</s>
<s>
The	O
Netfilter	B-Application
firewall	O
component	O
of	O
Linux	B-Operating_System
,	O
where	O
it	O
replaced	O
an	O
earlier	O
hash	B-Error_Name
function	I-Error_Name
that	O
was	O
too	O
sensitive	O
to	O
collisions	O
.	O
</s>
<s>
The	O
resulting	O
system	O
,	O
however	O
,	O
was	O
shown	O
to	O
still	O
be	O
sensitive	O
to	O
hash	B-Error_Name
flooding	O
attacks	O
,	O
even	O
when	O
the	O
Jenkins	B-Error_Name
hash	I-Error_Name
is	O
randomized	O
using	O
a	O
secret	O
key	O
.	O
</s>
<s>
The	O
program	O
that	O
solved	O
the	O
game	O
of	O
kalah	O
used	O
the	O
Jenkins	B-Error_Name
hash	I-Error_Name
function	I-Error_Name
,	O
instead	O
of	O
the	O
Zobrist	B-Application
hashing	I-Application
technique	O
more	O
commonly	O
used	O
for	O
this	O
type	O
of	O
problem	O
;	O
the	O
reasons	O
for	O
this	O
choice	O
were	O
the	O
speed	O
of	O
Jenkins	O
 '	O
function	O
on	O
the	O
small	O
representations	O
of	O
kalah	O
boards	O
,	O
as	O
well	O
as	O
the	O
fact	O
that	O
the	O
basic	O
rule	O
of	O
kalah	O
can	O
radically	O
alter	O
the	O
board	O
,	O
negating	O
the	O
benefit	O
of	O
Zobrist	O
's	O
incremental	O
computation	O
of	O
hash	B-Error_Name
functions	I-Error_Name
.	O
</s>
<s>
The	O
lookup3	O
function	O
consumes	O
input	O
in	O
12	O
byte	B-Application
(	O
96	O
bit	O
)	O
chunks	O
.	O
</s>
<s>
Note	O
,	O
though	O
,	O
that	O
any	O
speed	O
improvement	O
from	O
the	O
use	O
of	O
this	O
hash	B-Error_Name
is	O
only	O
likely	O
to	O
be	O
useful	O
for	O
large	O
keys	O
,	O
and	O
that	O
the	O
increased	O
complexity	O
may	O
also	O
have	O
speed	O
consequences	O
such	O
as	O
preventing	O
an	O
optimizing	O
compiler	O
from	O
inlining	O
the	O
hash	B-Error_Name
function	I-Error_Name
.	O
</s>
<s>
In	O
2011	O
Jenkins	O
released	O
a	O
new	O
128-bit	O
hash	B-Error_Name
function	I-Error_Name
called	O
SpookyHash	O
.	O
</s>
<s>
The	O
short	O
method	O
for	O
less	O
than	O
192	O
bytes	B-Application
(	O
43	O
bytes	B-Application
)	O
:	O
</s>
<s>
The	O
standard	O
method	O
for	O
more	O
than	O
191	O
bytes	B-Application
(	O
219	O
bytes	B-Application
)	O
:	O
</s>
